Oil control valve is one of the key parts of a variable valve timing system. Currently, according to ways for supplying oil, existing oil control valves can be classified into two types which are oil control valves with an end oil supply and oil control valves with a side oil supply.
As shown in FIG. 1 to FIG. 2, an existing oil control valve with an end oil supply includes two parts which are respectively a proportional electromagnet 1 and a hydraulic element 2. Wherein, the proportional electromagnet 1 includes a movable armature 10. The hydraulic element 2 includes: a valve body 20 with one end fixedly connected with the proportional electromagnet 1 and another end provided with an oil inlet I; a filter 21 having an annular body portion 21a and a strainer 21b fixedly disposed on an inner circumferential surface of the annular body portion 21a, wherein the annular body portion 21a is fixedly disposed on an outer circumferential surface of the end of the valve body 20 provided with the oil inlet I, the strainer 21b is located at an outer side of the oil inlet I so that hydraulic oil can flow into the valve body 20 from the oil inlet I after being filtered by the filter 21; and a pushrod 22, a movable piston 23, a compression spring 24, a spring retainer 25 and a circlip 26 successively disposed in the valve body 20 from inside out (i.e., along a direction C from the proportional electromagnet 1 to the oil inlet I).
Wherein, two ends of the pushrod 22 along an axial direction are fixedly connected with the movable armature 10 and the piston 23, respectively; two ends of the compression spring 24 stand against an end portion of the piston 23 which is far away from the pushrod 22 and the spring retainer 25, respectively, and the compression spring 24 is in a compressed state; and the circlip 26 is fixed on an inner circumferential surface of the valve body 20 and stands against the spring retainer 25 along the axial direction.
However, the existing oil control valve with an end supply has following drawbacks: 1) the filter 21, the spring retainer 25 and the circlip 26 are separated from each other, which makes a structure of the oil control valve complicated, cost of the oil control valve increase. Further, the spring retainer 25, the circlip 26 and the filter 21 need to be assembled one by one, which makes an assembling process for the oil control valve cumbersome and time-consuming.
2) The annular body portion 21a of the filter 21 is made of steel, and the annular body portion 21a is in interference fit with the valve body 20. Therefore, the annular body portion 21a needs to be pried up by tools for detaching the filter 21 from the valve body 20. The filter 21 will be damaged during the detaching process, which makes the filter 21 unable to be reused.
3) The spring retainer 25 is formed by a punching process. However, it is hard to keep a high machining precision in the punching process. Therefore, in order to form a spring retainer 25 with high machining precision, requirement for the punching process is very strict, which increases manufacturing cost of the spring retainer 25.